The findings reinforce the health dangers of cooking with rudimentary fires or cookstoves in one of the world’s poorest countries, but the researchers point out that there is no local information to reach inhabitants. "Local information about pollution exposure levels in Mozambique is sorely needed to ground-truth [our] estimates," said Susan Anenberg of Environmental Health Analytics and the George Washington University, US.

Mozambique is thought to be highly vulnerable to the kind of extreme weather events produced by climate change, and the country also experiences high rates of morbidity and mortality from household air pollution. In rural areas, households typically use open fires or rudimentary biomass stoves, while in urban areas metal charcoal stoves are more common. Fine particulate matter and other pollution generated by this type of inefficient burning are known to be highly dangerous, with one previous study linking household pollution in Mozambique in 2015 to 18,000 premature deaths.

More efficient options are available: natural- or forced-draft stoves in rural areas, or modern charcoal stoves for urban environments. In addition there are gas stoves, which are inherently cleaner than those running on charcoal.

Anenberg and colleagues wanted to find out how beneficial these alternatives would be to Mozambicans. Having identified clean cookstoves that could find success in Mozambique, they estimated air-pollution exposure levels based on estimates for other parts of Africa. These estimates went into an atmospheric model and a health and climate-impact model to make a new estimate of the possible societal benefits, focusing in particular on deaths arising from stroke, heart disease, lung cancer, chronic obstructive pulmonary disorder and lower respiratory infections.

The researchers found that if just 10% of rural households in Mozambique got a natural-draft stove, the country could expect 200 fewer deaths related to fine particulate matter over three years; if the same households got forced-draft stoves, there could be 500 fewer deaths. Meanwhile, if 10% of households in five of Mozambique’s major cities got a gas stove, there could be 160 fewer premature deaths; modern charcoal stoves would obtain 80% of this benefit.

As for climate change, the researchers found that any of the better stove scenarios would reduce the contribution to temperature rise from cookstoves by 4–6% over the next century.

"We found that each type of cleaner cookstove examined led to improvements in air quality, avoided health impacts from air pollution, and less climate change-related temperature rise," said Anenberg. "The cleanest stoves were more health beneficial, but nearly all were cost-effective."

The researchers are now investigating the use of solid fuels for heating. "Burning solid fuels for heating degrades air quality and contributes to climate change, particularly in cold areas where the pollution gets transported to snow and ice covered regions and reduces the reflectivity of the planet," said Anenberg. "We are trying to determine the extent of solid fuel heating around the world, which types of fuels are commonly used in different places, and the impacts this practice has on public health and the environment."

The cookstove study is published in Environmental Research Letters (ERL).

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